Toggle Side Panel

Shopping Cart

No products in the basket.

Shopping Cart

No products in the basket.

Close search
Home / DTC / B1301 — Door electric locking relay coil circuit

B1301 — Door electric locking relay coil circuit

Detailed page for trouble code B1301.

34,344codes
59brands
11,853generic
22,491specific
All codes P-codes (Powertrain) B-codes (Body) C-codes (Chassis) U-codes (Network/User) Tesla Alerts
Reset
Code

B1301

ALFA ROMEO B — Body

Door electric locking relay coil circuit

Brand: ALFA ROMEO
Type: B — Body
AI status
Completed
ready
Completed 100%
Page language: EN

Causes

  • Blown fuse for central locking/relay feed
  • Faulty door lock relay (coil open or shorted)
  • Open, short or high-resistance wiring between relay and control unit
  • Corroded/loose connector pins at relay or BCM
  • Poor ground at relay or BCM ground point
  • BCM or relay driver transistor fault

Symptoms

  • Central/door locking fails to operate (no lock/unlock)
  • Intermittent locking/unlocking or only partial operation
  • Clicking from relay socket absent or present continuously
  • Blown fuse(s) related to body locks or recurring fuse failure
  • Battery drain when relay stuck on (rare)
  • Multiple doors behave the same (indicates common feed/relay/BCM)

What to check

  • Read DTCs with appropriate scan tool and confirm B1301 is current
  • Visual inspection of relay, fuse, connectors, and wiring for corrosion, damage or water ingress
  • Verify fuse(s) for central locking are intact and correct rating
  • Check for audible relay click when commanding locks from switch or scanner
  • Wiggle test harness at doors/hinges while actuating to reproduce intermittent fault
  • Inspect BCM connector for corrosion or bent pins

Signal parameters

  • Expected coil supply voltage when commanded: ~11–14.5 V (battery voltage)
  • Expected coil feed at rest: near 0 V (no command)
  • Typical relay coil resistance (varies by relay): roughly 50–300 Ω — consult OEM spec
  • Expected coil current when energized: approx 0.04–0.3 A depending on coil resistance
  • Ground continuity from relay ground pin to chassis/BCM ground:
  • Command signal from BCM: switched 12 V or ground depending on relay driver design (refer to wiring diagram)

Diagnostic algorithm

  1. Record freeze frame and all related codes; note when fault is present (ignition/accessory state).
  2. Perform a visual inspection of relay, fuse, relay socket, BCM connector and wiring harness; repair obvious damage.
  3. Verify the correct fuse(s) and replace if blown; re-test to see if code returns.
  4. With a DVOM, check for battery voltage at relay feed pin(s). If no feed, trace back to fuse/ignition feed.
  5. Command the lock/unlock while monitoring voltage at the relay coil pins. One coil pin should see battery voltage (or switched voltage) when commanded; the other should be switched to ground (or see voltage change).
  6. Remove relay and measure coil resistance on bench; compare to OEM spec. Replace relay if out of range or no continuity.
  7. Bench-test relay by applying 12 V to coil and confirm audible click and contact switching.
  8. If relay and supply are OK but no command signal, backprobe BCM output while commanding and check for proper driver behavior; if driver is inactive or shorted, consult wiring diagram and test continuity to BCM.
  9. Perform continuity/resistance checks on wiring between relay socket and BCM/ground; repair any opens/shorts. Protect and seal connectors if corrosion found.
  10. After repairs or relay replacement, clear codes and retest multiple cycles to confirm fault does not return. If wiring and relay OK and fault persists, consider BCM module diagnostic/repair per manufacturer procedure.

Likely causes

  • Relay coil open or internally shorted
  • Corroded or pushed-out connector at relay socket
  • Broken/chafed wire in door harness or near hinge area
  • Blown fuse protecting the relay coil circuit
  • Failed BCM output driver controlling the relay

Fault status

⚠️ Status
Body control module has detected an open/short/intermittent condition in the door locking relay coil circuit; relay may not energize reliably.
🟡 Repair difficulty: Medium
⏱️ Diagnostic time: 0.5-2.0 hours

Similar codes

B1299 B1300 B1302 B1310 U0100
89

Browse 89 ALFA ROMEO manuals: repair procedures, diagnostics, wiring diagrams, component locations, service data and Labor Times by year, model and trim.

ALFA ROMEO

Your experience will help others
+100 karma for a short comment :)
Keep it short and practical. Up to 500 characters.
Send to email
Code

B1301

FIAT B — Body

Door electric locking relay coil circuit

Brand: FIAT
Type: B — Body
AI status
Completed
ready
Completed 100%
Page language: EN

Causes

  • Blown fuse for central locking/relay feed
  • Faulty door lock relay (coil open or shorted)
  • Open, short or high-resistance wiring between relay and control unit
  • Corroded/loose connector pins at relay or BCM
  • Poor ground at relay or BCM ground point
  • BCM or relay driver transistor fault

Symptoms

  • Central/door locking fails to operate (no lock/unlock)
  • Intermittent locking/unlocking or only partial operation
  • Clicking from relay socket absent or present continuously
  • Blown fuse(s) related to body locks or recurring fuse failure
  • Battery drain when relay stuck on (rare)
  • Multiple doors behave the same (indicates common feed/relay/BCM)

What to check

  • Read DTCs with appropriate scan tool and confirm B1301 is current
  • Visual inspection of relay, fuse, connectors, and wiring for corrosion, damage or water ingress
  • Verify fuse(s) for central locking are intact and correct rating
  • Check for audible relay click when commanding locks from switch or scanner
  • Wiggle test harness at doors/hinges while actuating to reproduce intermittent fault
  • Inspect BCM connector for corrosion or bent pins

Signal parameters

  • Expected coil supply voltage when commanded: ~11–14.5 V (battery voltage)
  • Expected coil feed at rest: near 0 V (no command)
  • Typical relay coil resistance (varies by relay): roughly 50–300 Ω — consult OEM spec
  • Expected coil current when energized: approx 0.04–0.3 A depending on coil resistance
  • Ground continuity from relay ground pin to chassis/BCM ground:
  • Command signal from BCM: switched 12 V or ground depending on relay driver design (refer to wiring diagram)

Diagnostic algorithm

  1. Record freeze frame and all related codes; note when fault is present (ignition/accessory state).
  2. Perform a visual inspection of relay, fuse, relay socket, BCM connector and wiring harness; repair obvious damage.
  3. Verify the correct fuse(s) and replace if blown; re-test to see if code returns.
  4. With a DVOM, check for battery voltage at relay feed pin(s). If no feed, trace back to fuse/ignition feed.
  5. Command the lock/unlock while monitoring voltage at the relay coil pins. One coil pin should see battery voltage (or switched voltage) when commanded; the other should be switched to ground (or see voltage change).
  6. Remove relay and measure coil resistance on bench; compare to OEM spec. Replace relay if out of range or no continuity.
  7. Bench-test relay by applying 12 V to coil and confirm audible click and contact switching.
  8. If relay and supply are OK but no command signal, backprobe BCM output while commanding and check for proper driver behavior; if driver is inactive or shorted, consult wiring diagram and test continuity to BCM.
  9. Perform continuity/resistance checks on wiring between relay socket and BCM/ground; repair any opens/shorts. Protect and seal connectors if corrosion found.
  10. After repairs or relay replacement, clear codes and retest multiple cycles to confirm fault does not return. If wiring and relay OK and fault persists, consider BCM module diagnostic/repair per manufacturer procedure.

Likely causes

  • Relay coil open or internally shorted
  • Corroded or pushed-out connector at relay socket
  • Broken/chafed wire in door harness or near hinge area
  • Blown fuse protecting the relay coil circuit
  • Failed BCM output driver controlling the relay

Fault status

⚠️ Status
Body control module has detected an open/short/intermittent condition in the door locking relay coil circuit; relay may not energize reliably.
🟡 Repair difficulty: Medium
⏱️ Diagnostic time: 0.5-2.0 hours

Similar codes

B1299 B1300 B1302 B1310 U0100
Repair manuals

Manual library for FIAT

26

Browse 26 FIAT manuals: repair procedures, diagnostics, wiring diagrams, component locations, service data and Labor Times by year, model and trim.

FIAT

Your experience will help others
+100 karma for a short comment :)
Keep it short and practical. Up to 500 characters.
Send to email
Code

B1301

MITSUBISHI B — Body

5bow sensor:Up&Down=ON

Brand: MITSUBISHI
Type: B — Body
AI status
Completed
ready
Completed 100%
Page language: EN

Causes

  • Blown fuse for central locking/relay feed
  • Faulty door lock relay (coil open or shorted)
  • Open, short or high-resistance wiring between relay and control unit
  • Corroded/loose connector pins at relay or BCM
  • Poor ground at relay or BCM ground point
  • BCM or relay driver transistor fault

Symptoms

  • Central/door locking fails to operate (no lock/unlock)
  • Intermittent locking/unlocking or only partial operation
  • Clicking from relay socket absent or present continuously
  • Blown fuse(s) related to body locks or recurring fuse failure
  • Battery drain when relay stuck on (rare)
  • Multiple doors behave the same (indicates common feed/relay/BCM)

What to check

  • Read DTCs with appropriate scan tool and confirm B1301 is current
  • Visual inspection of relay, fuse, connectors, and wiring for corrosion, damage or water ingress
  • Verify fuse(s) for central locking are intact and correct rating
  • Check for audible relay click when commanding locks from switch or scanner
  • Wiggle test harness at doors/hinges while actuating to reproduce intermittent fault
  • Inspect BCM connector for corrosion or bent pins

Signal parameters

  • Expected coil supply voltage when commanded: ~11–14.5 V (battery voltage)
  • Expected coil feed at rest: near 0 V (no command)
  • Typical relay coil resistance (varies by relay): roughly 50–300 Ω — consult OEM spec
  • Expected coil current when energized: approx 0.04–0.3 A depending on coil resistance
  • Ground continuity from relay ground pin to chassis/BCM ground:
  • Command signal from BCM: switched 12 V or ground depending on relay driver design (refer to wiring diagram)

Diagnostic algorithm

  1. Record freeze frame and all related codes; note when fault is present (ignition/accessory state).
  2. Perform a visual inspection of relay, fuse, relay socket, BCM connector and wiring harness; repair obvious damage.
  3. Verify the correct fuse(s) and replace if blown; re-test to see if code returns.
  4. With a DVOM, check for battery voltage at relay feed pin(s). If no feed, trace back to fuse/ignition feed.
  5. Command the lock/unlock while monitoring voltage at the relay coil pins. One coil pin should see battery voltage (or switched voltage) when commanded; the other should be switched to ground (or see voltage change).
  6. Remove relay and measure coil resistance on bench; compare to OEM spec. Replace relay if out of range or no continuity.
  7. Bench-test relay by applying 12 V to coil and confirm audible click and contact switching.
  8. If relay and supply are OK but no command signal, backprobe BCM output while commanding and check for proper driver behavior; if driver is inactive or shorted, consult wiring diagram and test continuity to BCM.
  9. Perform continuity/resistance checks on wiring between relay socket and BCM/ground; repair any opens/shorts. Protect and seal connectors if corrosion found.
  10. After repairs or relay replacement, clear codes and retest multiple cycles to confirm fault does not return. If wiring and relay OK and fault persists, consider BCM module diagnostic/repair per manufacturer procedure.

Likely causes

  • Relay coil open or internally shorted
  • Corroded or pushed-out connector at relay socket
  • Broken/chafed wire in door harness or near hinge area
  • Blown fuse protecting the relay coil circuit
  • Failed BCM output driver controlling the relay

Fault status

⚠️ Status
Body control module has detected an open/short/intermittent condition in the door locking relay coil circuit; relay may not energize reliably.
🟡 Repair difficulty: Medium
⏱️ Diagnostic time: 0.5-2.0 hours

Similar codes

B1299 B1300 B1302 B1310 U0100
406

Browse 406 MITSUBISHI manuals: repair procedures, diagnostics, wiring diagrams, component locations, service data and Labor Times by year, model and trim.

MITSUBISHI

Your experience will help others
+100 karma for a short comment :)
Keep it short and practical. Up to 500 characters.
Send to email
Code

B1301

Other B — Body

Power Door Lock Circuit Open

Brand: Other
Type: B — Body
AI status
Completed
ready
Completed 100%
Page language: EN

Causes

  • Blown fuse for central locking/relay feed
  • Faulty door lock relay (coil open or shorted)
  • Open, short or high-resistance wiring between relay and control unit
  • Corroded/loose connector pins at relay or BCM
  • Poor ground at relay or BCM ground point
  • BCM or relay driver transistor fault

Symptoms

  • Central/door locking fails to operate (no lock/unlock)
  • Intermittent locking/unlocking or only partial operation
  • Clicking from relay socket absent or present continuously
  • Blown fuse(s) related to body locks or recurring fuse failure
  • Battery drain when relay stuck on (rare)
  • Multiple doors behave the same (indicates common feed/relay/BCM)

What to check

  • Read DTCs with appropriate scan tool and confirm B1301 is current
  • Visual inspection of relay, fuse, connectors, and wiring for corrosion, damage or water ingress
  • Verify fuse(s) for central locking are intact and correct rating
  • Check for audible relay click when commanding locks from switch or scanner
  • Wiggle test harness at doors/hinges while actuating to reproduce intermittent fault
  • Inspect BCM connector for corrosion or bent pins

Signal parameters

  • Expected coil supply voltage when commanded: ~11–14.5 V (battery voltage)
  • Expected coil feed at rest: near 0 V (no command)
  • Typical relay coil resistance (varies by relay): roughly 50–300 Ω — consult OEM spec
  • Expected coil current when energized: approx 0.04–0.3 A depending on coil resistance
  • Ground continuity from relay ground pin to chassis/BCM ground:
  • Command signal from BCM: switched 12 V or ground depending on relay driver design (refer to wiring diagram)

Diagnostic algorithm

  1. Record freeze frame and all related codes; note when fault is present (ignition/accessory state).
  2. Perform a visual inspection of relay, fuse, relay socket, BCM connector and wiring harness; repair obvious damage.
  3. Verify the correct fuse(s) and replace if blown; re-test to see if code returns.
  4. With a DVOM, check for battery voltage at relay feed pin(s). If no feed, trace back to fuse/ignition feed.
  5. Command the lock/unlock while monitoring voltage at the relay coil pins. One coil pin should see battery voltage (or switched voltage) when commanded; the other should be switched to ground (or see voltage change).
  6. Remove relay and measure coil resistance on bench; compare to OEM spec. Replace relay if out of range or no continuity.
  7. Bench-test relay by applying 12 V to coil and confirm audible click and contact switching.
  8. If relay and supply are OK but no command signal, backprobe BCM output while commanding and check for proper driver behavior; if driver is inactive or shorted, consult wiring diagram and test continuity to BCM.
  9. Perform continuity/resistance checks on wiring between relay socket and BCM/ground; repair any opens/shorts. Protect and seal connectors if corrosion found.
  10. After repairs or relay replacement, clear codes and retest multiple cycles to confirm fault does not return. If wiring and relay OK and fault persists, consider BCM module diagnostic/repair per manufacturer procedure.

Likely causes

  • Relay coil open or internally shorted
  • Corroded or pushed-out connector at relay socket
  • Broken/chafed wire in door harness or near hinge area
  • Blown fuse protecting the relay coil circuit
  • Failed BCM output driver controlling the relay

Fault status

⚠️ Status
Body control module has detected an open/short/intermittent condition in the door locking relay coil circuit; relay may not energize reliably.
🟡 Repair difficulty: Medium
⏱️ Diagnostic time: 0.5-2.0 hours

Similar codes

B1299 B1300 B1302 B1310 U0100
7,698

The library contains 7,698 repair and diagnostic manuals. Choose a brand to open the full manual tree by year, model and trim.

ALFA ROMEO
89
AUDI
1,160
BMW
479
CHEVROLET
16
DAEWOO
75
FIAT
26
GENESIS
207
HUMMER
138
HYUNDAI
371
ISUZU
86
LAND ROVER
320
LEXUS
280
LINCOLN
166
MERCEDES-BENZ
856
MERCURY
296
MITSUBISHI
406
PORSCHE
136
TESLA
58
TOYOTA
2,042
TRIUMPH
131
VOLKSWAGEN
139
VOLVO
221
Your experience will help others
+100 karma for a short comment :)
Keep it short and practical. Up to 500 characters.
Send to email

Report

Harassment or bullying behavior
Contains mature or sensitive content
Contains misleading or false information
Contains abusive or derogatory content
Contains spam, fake content or potential malware

Block Member?

Please confirm you want to block this member.

You will no longer be able to:

  • See blocked member's posts
  • Mention this member in posts
  • Invite this member to groups
  • Message this member
  • Add this member as a connection

Please note: This action will also remove this member from your connections and send a report to the site admin. Please allow a few minutes for this process to complete.

Report

You have already reported this .